使用通用时出现问题

Question

我有以下 Genric class 用于设置任何自定义数据类型

        public class NotificationData<E> {
            private E element;
            public E getElement() {
                return element;
            }

下方显示编译时错误的通知任务界面 -

T cannot be resolved to a type. I add "" in front of the method it does resolve error but creating issue for other classes which are using this interface.

public interface NotificationTask {
             void execute(NotificationData<T> taskData);
            // --other methods
}

下面class实现了它但是显示错误

Name clash: The method execute(NotificationData) of type AbstractEmailNotificationTask has the same erasure as execute(NotificationData) of type NotificationTask but does not override it

和 prepareEmailTemplate 显示以下错误-

The method prepareEmailTemplate(NotificationData) from the type AbstractEmailNotificationTask refers to the missing type T

public abstract class AbstractEmailNotificationTask implements NotificationTask{
    private static final Log logger = LogFactory.getLog(AbstractEmailNotificationTask.class);
    private boolean  flag;

    public <T> void execute(NotificationData<?> taskData) {
        try {
            String content=prepareEmailTemplate(taskData);
            setTaskExceuted(true);
        } catch (Exception e) {
            logger.debug (e.getMessage (),e);
            setTaskExceuted(false);
        }
    }
    abstract protected  String prepareEmailTemplate(NotificationData<T> taskData) throws TaskExecutionException;
}



public class AddressUpdateEmailNotification extends AbstractEmailNotificationTask {
            public AddressUpdateEmailNotification() {
            }

            @Override
            protected  String prepareEmailTemplate(NotificationData<CustomerAddress> taskData) {
                CustomerAddress customerAddress= taskData.getElement();
                return customerAddress.getCity() +":"+customerAddress.getState().getStateName();
            }

        }

以上是将实施 prepareEmail 模板的实际 class。在此 class 中，我传递了 CustomerAddress，但在扩展 AbstractEmailNotificationTask 的其他类中，我必须传递其他对象。我想使用通用但面临这些问题。

Answer 1

您的接口不是泛型的，因此其中的方法无法被泛型类型识别（并且无法解析为一个）。简单地使其通用：

public interface NotificationTask<T> {
    void execute(NotificationData<T> taskData);
    // --other methods
}

使用通用时出现问题

Issue while using generic

java

generics